1. Field of the Invention
The present invention relates to a method of and apparatus for recording and reproducing data for use with a computer system having a floppy disk drive, for example.
2. Description of the Prior Art
Heretofore, computers such as a personal computer and a work station or electronic equipment (e.g., music sequencers, devices sampling, etc. ) incorporating therein a microcomputer or the like house therein a floppy disk drive or they are connected to a floppy disk drive through an extended bus or the like to use the floppy disk drive.
It is customary that a floppy disk drive records data supplied thereto from the host equipment on a floppy disk set thereon or reproduces and supplies data recorded on the floppy disk to the host equipment on the basis of various commands supplied thereto from the host equipment such as a computer or the like.
FIG. 1 of the accompanying drawings shows a recording format used in a conventional floppy disk drive. The recording format of the floppy disk drive will be described with reference to FIG. 1.
In FIG. 1, reference symbol Idx depicts an index signal generated from a floppy disk drive mechanism to represent a starting portion of a track. Reference symbol Tp depicts a track pattern. Reference symbol "4E" shown on the leftmost portion of the track pattern Tp represents a gap G4a recorded on the starting portion of the track to protect data from a displacement of an index detection timing between the floppy disk drives. Reference symbol "00" represents a synchronizing (sync) signal SY, and reference symbols "C2" and "FC" depict an index address mark IAM used to detect the starting portion of the track. Reference symbol "4E" depicts a gap G1 used to discriminate the index address mark IAM and an identification number ID.
The next sector starts from the gap G1, and a sector 1, a sector 2, . . . , a sector n are continued as shown in FIG. 1. As shown by the area of the sector 1 in FIG. 1, each sector comprises an identification number ID, a gap G2 used to discriminate the identification number ID and data DA, the data DA and a gap G3 used to discriminate the sectors.
A magnetic head used by the floppy disk drive to record and reproduce data will be described with reference to FIG. 2. As shown in FIG. 2, there is provided a tunnel erase head 1, and a floppy disk (not shown) is rotated in the direction shown by a solid arrow A in FIG. 2. The tunnel erase head 1 includes a read write gap 1RWG and an erase gap 1EG. Upon recording, the tunnel erase head 1 records data by the read write gap 1RWG and generates a guardband of the tracks by the erase gap 1EG.
FIG. 3 shows a timing at which the floppy disk drive using the tunnel erase head 1 records data. In FIG. 3, reference symbol Tp depicts a track pattern, and WGP depicts a write gate pulse supplied from the host equipment (not shown). Reference symbols WP and EP depict a write signal and an erase signal generated in the inside of the floppy disk drive (not shown), respectively. When the tunnel erase head 1 is applied to the track pattern TP shown in FIG. 3, the read write gap 1RWG and the erase gap 1EG of the tunnel erase head 1 shown in FIG. 2 are reversed in position.
FIG. 3 shows the case that an area of data DA (shown hatched) of a certain track is rewritten. Specifically, when the area shown hatched is rewritten, the write gate pulse WGP is supplied from the host equipment, and the write signal WP and the erase signal EP are supplied from the floppy disk drive. As shown in FIG. 3, when the write gate pulse WGP is turned on, i.e., goes to logic low "0" level, then the write signal WP is turned on, i.e., goes to logic low "0" level. After a predetermined delay time D1 (i.e., erase-on delay), the erase signal EP is turned on. When the write gate pulse WGP is turned off, i.e., goes to logic high "1" level, then the write signal WP is turned off, i.e., goes to logic high "1" level. After a predetermined delay time D2 (erase-off delay), the erase signal EP is turned off, i.e., goes to logic high "1" level.
More specifically, when the tunnel erase head 1 is used, the erase pulse or signal EP is turned on and off with the predetermined delay times D1, D2 relative to the level of the write gate pulse WGP so that the erase signal EP goes to logic low "0" level during the gap G2 and goes to logic high "1" level during the gap G3.
The pre-erase head 2 shown in FIG. 2 includes an erase gap 2EG and a read write gap 2RWG. Upon recording, the pre-erase head 2 erases recorded data by the erase gap 2EG and then records data by the read write gap 2RWG.
FIG. 4 shows a timing at which the floppy disk drive using the pre-erase head 2 records data. In FIG. 4, reference symbol TP depicts a track pattern, and reference symbols WP and EP depict a write signal and an erase signal generated in the inside of the floppy disk drive (not shown). Reference symbol WPG depicts a write gate pulse supplied from a host equipment (not shown), and reference symbol Wda depicts data to be recorded. When the pre-erase head 2 shown in FIG. 2 is applied to the track pattern shown in FIG. 4, the read write gap 2RWG and the erase gap 2EG of the pre-erase head 2 shown in FIG. 2 are reversed in position.
FIG. 4 shows the case that the area of data DA (shown hatched) of a certain track is rewritten. Specifically, when the area shown hatched is rewritten, the write gate pulse WGP is supplied from the host equipment and the erase signal EP and the write pulse WP are supplied from the floppy disk drive. As shown in FIG. 4, when the write gate pulse WGP is turned on, i.e., goes to logic low "0" level, then the erase signal EP and the write signal WP are turned on, i.e., go to logic low "0" level. Also, when the write gate pulse WGP is turned off, i.e., goes to logic high "1" level, the erase signal EP is turned off, i.e., goes to logic high "1" level. After a predetermined time, the write signal WP is turned off, i.e., goes to logic high "1" level.
Specifically, when the pre-erase head 2 is used, the write gate pulse WGP and the erase pulse EP are simultaneously turned on and off so that the erase signal EP is turned on at the position of the gap G2 and turned off at the position of the gap G3. Since the pre-erase head 2 pre-erases (erases previously) the area of the data DA reliably, the pre-erase head 2 begins to record data from the intermediate portion of the gap G2 prior to the data DA to thereby record the gap data "4E" corresponding to the distance between the read write gap 2RWG and the erase gap 2EG.
As shown in FIG. 2, since the erase gap 2EG in the pre-erase head 2 is ahead of the read write gap 2RWG relative to the recording medium, if the pre-erase head 2 is activated when the position of the read write gap 2RWG becomes equal to the position of the gap G2, then a portion NEt which is not pre-erased by the pre-erase head 2 is produced on one portion of the gap G2 of the track pattern TP.
FIG. 5 shows a timing at which the floppy disk drive using the pre-erase head 2 records data. A format shown in FIG. 5 is different from that shown in FIG. 4. As is clear from the track pattern TP, according to the format shown in FIG. 5, an index signal Idx goes to logic high "1" level in the gap G1 which is followed by sectors of one track ranging from a sector 1 to a sector n. Each sector comprises an identification number ID, data DA and a gap G3 used to discriminate the sectors.
In FIG. 5, reference symbol Idx depicts an index signal, and reference symbol TP depicts a track pattern. The track pattern TP of one track amount is shown on the upper portion of FIG. 5, and the track pattern TP is shown on the lower portion of FIG. 5 in an enlarged scale. Further, in FIG. 5, reference symbol WGP depicts a write gate pulse supplied from the host equipment (not shown), and reference symbols WP and EP depict a write signal and an erase signal generated from the inside of the floppy disk drive (not shown). When the pre-erase head 2 shown in FIG. 2 is applied to the track pattern TP shown in FIG. 5, the read write gap 2RWG and the erase gap 2EG of the pre-erase head 2 shown in FIG. 2 are reversed in position.
FIG. 5 shows the case that the area of the data DA (shown hatched) of a certain track is rewritten. Specifically, when the area shown hatched in FIG. 5 is rewritten, the write gate pulse WGP is supplied from the host equipment, and the write signal WP and the erase signal EP are supplied from the floppy disk drive (not shown). As shown in FIG. 5, when the write gate pulse WGP is turned on, i.e., goes to logic low "0" level, the write signal WP and the erase signal EP are turned on, i.e., go to logic low "0" level. Also, when the write gate pulse WGP is turned off, i.e., goes to logic high "1" level, the erase signal EP is turned off, i.e., goes to logic high "1" level. After a predetermined time, the write signal WP is turned off, i.e, goes to logic high "1" level.
Specifically, when the pre-erase head 2 is used, the pre-erase head 2 is activated (erase-on) in the area of the data DA of the track pattern TP and is disabled (erase-off) in the gap G3. As earlier noted, since the erase gap 2EG in the pre-erase head 2 is ahead of the read write gap 2RWG relative to the recording medium, if the pre-erase head 2 is activated (erase-on) when the position of the read write gap 2RWG becomes equal to the starting position of the data DA, then the portion NEt, which is not pre-erased, is produced in one portion of the area of the data DA of the track pattern TP.
When the tunnel erase head 1 shown in FIG. 2 is used according to the format shown in FIG. 3 and when the pre-erase head 2 shown in FIG. 2 is used according to the format shown in FIG. 4, one track needs a number of gaps, such as the gap G1 used to discriminate the index address mark IAM and the gap G2, the gap G3 used to discriminate the sectors, in addition to the index address mark IAM.
In order to pre-erase (previously erase) the area of the data DA reliably, the pre-erase head 2 starts recording data from the intermediate portion of the gap G2 prior to the data DA to thereby record the gap data "4E" corresponding to the distance between the read write gap 2RWG and the erase gap 2EG. Therefore, the relatively wide gaps are formed. From a high density recording standpoint, it is not desirable that the recording area is consumed by the wide gaps.
Further, when the pre-erase head 2 shown in FIG. 2 is used according to the format shown in FIG. 5, no gap exists between the identification number ID and the data DA in the format shown in FIG. 5 so that the portion NEt, which is not pre-erased, is produced in a starting portion of the area of the data DA as shown in FIG. 5. As a consequence, when data is recorded, data is recorded on the portion NEt which is not pre-erased with the result that data cannot be recorded satisfactorily.